The present invention relates to a thermistor element, a thermistor element production method and a thermistor temperature sensor.
A thermistor element is generally produced from a sintered conductive oxide that shows a change in resistance (specific resistance) with a change of temperature and is suitably used in a temperature sensor. Japanese Laid-Open Patent Publication No. 11-251109 discloses one type of thermistor element having a thermistor body formed of a sintered conductive oxide with a perovskite phase of e.g. Y(Cr, Mn)O3 or Y(Cr, Mn)O3 and a metal oxide phase of e.g. Y2O3 or Al2O3.
In the case of using the thermistor element or thermistor temperature sensor in an internal combustion engine to measure the temperature of engine exhaust gas, there has recently been a demand for the thermistor element to enable temperature measurements in a high temperature range of around 900° C. for the protection of a diesel particulate filter (DPF) and a NOx reduction catalyst in the engine. There has also been a demand for the thermistor element to enable temperature measurements in a low temperature range for the application of on-board diagnostics (OBD). The thermistor element may thus be required to carry out temperature measurements over the wide range from a low temperature of −40° C. to a high temperature of 900° C. or higher. In order to protect the thermistor element from condensation and soot in the measurement gas during the temperature measurements over such a wide temperature range, a metal tube of e.g. stainless alloy is provided to accommodate therein the thermistor element.